Aircraft manufacturers are under an increasing pressure to produce lightweight, strong and resistant aircraft which also has the lowest productions costs and also low costs for maintenance during the entire lifetime of the aircraft. An aircraft must be strong enough to cope with stresses during take-off, high altitude cruising and landing, and at the same time it must be as easy as possible to maximise the performance of the aircraft. Partly because of this, aircraft manufacturers have started to use fibre reinforced resin matrix composites.
Such fibre reinforced resin matrix composites provide improved strength, wear resistance, rigidity and strength-weight relationship by comprising strong, rigid carbon fibres in a softer, more tensile resin matrix. The resin matrix material transmits forces to the fibres and provides stretching and toughness characteristics, since the fibres bear a major part of the applied forces.
Known methods for producing fibre reinforced resin matrix composites for an aircraft comprise that a number of so called prepreg sheets, or simply abbreviated as “prepregs” are put on top of each other in contact with a moulding tool. The prepreg consists of unidirectional fibres or multi-directional fibres in an uncured resin. A vacuum bag is placed over and is sealed towards the moulding tool so that the entire component is completely enclosed. Vacuum is then applied to the enclosed component so that the prepregs are becoming compacted towards the surface of the moulding tool.
When producing composite spars, it is cost efficient to arrange the majority of, or all of, the prepreg sheets (e.g. [0/90/±45]) of a composite laminate plane, and thereafter form down the flanges. This is relatively simple as long as the forming takes place along a straight line. Problem arises when the surface to be shaped is not straight—e.g. when bending alongside a curved line or trumpet form, for instance when producing wing spars for some airplanes, so called trumpet spars.
Thus, there is a need to provide a method to in a simple manner produce composite components with one or more curved surfaces.